Boron and Nitrogen Co-Doped Trimodal-Porous Wood-Derived Carbon for Boosting Capacitive Performance

Heteroatom doping and a porous structure are two significant factors that improve the capacitance performance of carbon-based electrodes, but there are often one-sided considerations between them. Herein, effective B, N co-doping and trimodal-porous structure from the carbonization of sustainable natural wood are obtained at the same time. The unique pore structure is coarsely tuned by a modified ZnAc₂-assisted hypersaline route and further fine-tuned by controlling the doping levels of boron and nitrogen. The high specific surface area of porous carbon up to 1201 m²g^-1 is coordinated with the trimodal foam-like nanopores. This carbon-based material as a supercapacitor electrode can provide not only trimodal-porous ion transfer highways but also doping-induced pseudocapacitance. The resulting pore and heteroatom reengineered wood-derived carbon harvests a remarkable capacitance of 479 F g^-1 at 1 A g^-1, among the highest values in reported B, N co-doped carbon electrodes. The aqueous symmetric supercapacitor exhibits energy density of 18.5 Wh kg^-1 and power density of 6.4 kW kg^-1, along with >90% capacitance retention, both in H₂SO₄ and Li₂SO₄ electrolyte over 10 000 cycles. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim